Battery thermal management system for electrified vehicle

ABSTRACT

A battery thermal management system according to an exemplary aspect of the present disclosure includes, among other things, a heat spreader, a coolant channel attached to the heat spreader and a supply manifold fluidly connected with the coolant channel and configured to supply a heat transfer medium to the coolant channel. A return manifold is fluidly connected with the coolant channel and configured to expel the heat transfer medium from the coolant channel.

TECHNICAL FIELD

This disclosure relates to electrified vehicles, and more particularly,but not exclusively, to a battery thermal management system capable ofmaintaining battery cells of a battery system within a desiredtemperature range.

BACKGROUND

Hybrid electric vehicles (HEV's), plug-in hybrid electric vehicles(PHEV's), battery electric vehicles (BEV's), fuel cell vehicles andother known electrified vehicles differ from conventional motor vehiclesin that they are powered by one or more electric machines (i.e.,electric motors and/or generators) instead of or in addition to aninternal combustion engine. High voltage current for powering thesetypes of electric machine(s) is typically supplied by a traction batterysystem having one or more battery cells that store energy.

Battery systems are typically constructed of one or more battery modulesthat each includes a plurality of battery cells. In some conditions,heat is generated in the battery cells. This heat may need to be removedto improve battery cell capacity, life and performance. The batterycells may alternatively need heated in order to function properly inother conditions, such as extremely cold ambient conditions.

SUMMARY

A battery thermal management system according to an exemplary aspect ofthe present disclosure includes, among other things, a heat spreader, acoolant channel attached to the heat spreader and a supply manifoldfluidly connected with the coolant channel and configured to supply aheat transfer medium to the coolant channel. A return manifold isfluidly connected with the coolant channel and configured to expel theheat transfer medium from the coolant channel.

In a further non-limiting embodiment of the foregoing system, the heatspreader is in contact with a battery cell.

In a further non-limiting embodiment of either of the foregoing systems,the system includes a plurality of battery cells and a plurality of heatspreaders, at least one of the plurality of heat spreaders interspersedbetween adjacent battery cells of the plurality of battery cells.

In a further non-limiting embodiment of any of the foregoing systems,the heat spreader is an annealed pyrolytic graphite plate or a flexiblegraphite sheet.

In a further non-limiting embodiment of any of the foregoing systems, asecond coolant channel is attached to an opposite edge of the heatspreader from the coolant channel.

In a further non-limiting embodiment of any of the foregoing systems, avacuum insulation panel is beneath the heat spreader.

In a further non-limiting embodiment of any of the foregoing systems, afilm heater is on a first side of the vacuum insulation panel and a baseis on a second side of the vacuum insulation panel.

In a further non-limiting embodiment of any of the foregoing systems,the heat transfer medium is a liquid coolant.

In a further non-limiting embodiment of any of the foregoing systems,the coolant channel includes at least one augmentation feature.

In a further non-limiting embodiment of any of the foregoing systems, acentral supply line delivers the heat transfer medium to the supplymanifold and a central return line communicates the heat transfer mediumaway from the coolant channel.

A battery system according to another exemplary aspect of the presentdisclosure includes, among other things, a battery module having atleast one battery cell and a battery thermal management systemconfigured to heat the at least one battery cell with a film heater inresponse to a first temperature condition and cool the at least onebattery cell by transferring heat into a heat spreader in response to asecond temperature condition.

In a further non-limiting embodiment of the foregoing system, thebattery thermal management system includes the heat spreader adjacent tothe at least one battery cell, a coolant channel attached to the heatspreader, a supply manifold near a first side of the coolant channel anda return manifold near a second side of the coolant channel.

In a further non-limiting embodiment of either of the foregoing systems,the battery thermal management system include a heat exchangerconfigured to cool a heat transfer medium communicated through thecoolant channel.

In a further non-limiting embodiment of any of the foregoing systems,the battery thermal management system includes a base that supports theat least one battery cell.

In a further non-limiting embodiment of any of the foregoing systems, avacuum insulation panel is mounted to the base.

In a further non-limiting embodiment of any of the foregoing systems,the film heater is positioned between the vacuum insulation panel andthe at least one battery cell.

A method according to another exemplary aspect of the present disclosureincludes, among other things, transferring heat from a battery cell to aheat spreader, conducting the heat from the heat spreader into a coolantchannel and dissipating the heat into a heat transfer mediumcommunicated inside the coolant channel to thermally manage the batterycell.

In a further non-limiting embodiment of the foregoing method, the methodincludes the step of sensing a temperature condition of the batterycell.

In a further non-limiting embodiment of either of the foregoing methods,the method includes the step of heating the battery cell in response tothe temperature condition indicating a cold ambient condition.

In a further non-limiting embodiment of any of the foregoing methods,the method includes commanding the dissipating step in response to thetemperature condition indicating a hot ambient condition.

The embodiments, examples and alternatives of the preceding paragraphs,the claims, or the following description and drawings, including any oftheir various aspects or respective individual features, may be takenindependently or in any combination. Features described in connectionwith one embodiment are applicable to all embodiments, unless suchfeatures are incompatible.

The various features and advantages of this disclosure will becomeapparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a powertrain of an electrified vehicle.

FIG. 2 illustrates a front view of a battery module of an electrifiedvehicle.

FIG. 3 illustrates a top view of the battery module of FIG. 2.

FIG. 4 illustrates another battery module.

FIG. 5 illustrates a cooling channel of a battery thermal managementsystem.

FIG. 6 illustrates a battery thermal management system for thermallymanaging a battery system.

DETAILED DESCRIPTION

This disclosure relates to a battery module for use in an electrifiedvehicle. The exemplary battery module includes a battery thermalmanagement system capable of thermally managing one or more batterycells of the battery module. For example, the battery thermal managementsystem described herein may be employed to heat and/or cool the batterycells in order to maintain the battery cells within a desiredtemperature range over a full range of ambient conditions. These andother features are described in this disclosure.

FIG. 1 schematically illustrates a powertrain 10 for an electrifiedvehicle 12, such as a HEV. Although depicted as a HEV, it should beunderstood that the concepts described herein are not limited to HEV'sand could extend to other electrified vehicles, including but notlimited to, PHEV's, BEV's, and fuel cell vehicles.

In one embodiment, the powertrain 10 is a powersplit system that employsa first drive system that includes a combination of an engine 14 and agenerator 16 (i.e., a first electric machine) and a second drive systemthat includes at least a motor 36 (i.e., a second electric machine), thegenerator 16 and a traction battery system 50. For example, the motor36, the generator 16 and the traction battery system 50 may make up anelectric drive system 25 of the powertrain 10. The first and seconddrive systems generate torque to drive one or more sets of vehicle drivewheels 30 of the electrified vehicle 12, as discussed in greater detailbelow.

The engine 14, such as an internal combustion engine, and the generator16 may be connected through a power transfer unit 18. In onenon-limiting embodiment, the power transfer unit 18 is a planetary gearset. Of course, other types of power transfer units, including othergear sets and transmissions, may be used to connect the engine 14 to thegenerator 16. The power transfer unit 18 may include a ring gear 20, asun gear 22 and a carrier assembly 24. The generator 16 is driven by thepower transfer unit 18 when acting as a generator to convert kineticenergy to electrical energy. The generator 16 can alternatively functionas a motor to convert electrical energy into kinetic energy, therebyoutputting torque to a shaft 26 connected to the carrier assembly 24 ofthe power transfer unit 18. Because the generator 16 is operativelyconnected to the engine 14, the speed of the engine 14 can be controlledby the generator 16.

The ring gear 20 of the power transfer unit 18 may be connected to ashaft 28 that is connected to vehicle drive wheels 30 through a secondpower transfer unit 32. The second power transfer unit 32 may include agear set having a plurality of gears 34A, 34B, 34C, 34D, 34E, and 34F.Other power transfer units may also be suitable. The gears 34A-34Ftransfer torque from the engine 14 to a differential 38 to providetraction to the vehicle drive wheels 30. The differential 38 may includea plurality of gears that enable the transfer of torque to the vehicledrive wheels 30. The second power transfer unit 32 is mechanicallycoupled to an axle 40 through the differential 38 to distribute torqueto the vehicle drive wheels 30.

The motor 36 can also be employed to drive the vehicle drive wheels 30by outputting torque to a shaft 46 that is also connected to the secondpower transfer unit 32. In one embodiment, the motor 36 and thegenerator 16 are part of a regenerative braking system in which both themotor 36 and the generator 16 can be employed as motors to outputtorque. For example, the motor 36 and the generator 16 can each outputelectrical power to a high voltage bus 48 and the traction batterysystem 50. The traction battery system 50 may be a high voltage batterythat is capable of outputting electrical power to operate the motor 36and the generator 16. Other types of energy storage devices and/oroutput devices can also be incorporated for use with the electrifiedvehicle 12. The traction battery system 50 may be made up of one or morebattery modules that include battery cells that store the energynecessary to power the motor 36 and/or generator 16.

The motor 36, the generator 16, the power transfer unit 18, and thepower transfer unit 32 may generally be referred to as a transaxle 42,or transmission, of the electrified vehicle 12. Thus, when a driverselects a particular shift position, the transaxle 42 is appropriatelycontrolled to provide the corresponding gear for advancing theelectrified vehicle 12 by providing traction to the vehicle drive wheels30.

The powertrain 10 may additionally include a control system 44 formonitoring and/or controlling various aspects of the electrified vehicle12. For example, the control system 44 may communicate with the electricdrive system 25, the power transfer units 18, 32 or other components tomonitor and/or control the electrified vehicle 12. The control system 44includes electronics and/or software to perform the necessary controlfunctions for operating the electrified vehicle 12. In one embodiment,the control system 44 is a combination vehicle system controller andpowertrain control module (VSC/PCM). Although it is shown as a singlehardware device, the control system 44 may include multiple controllersin the form of multiple hardware devices, or multiple softwarecontrollers within one or more hardware devices.

A controller area network (CAN) 52 allows the control system 44 tocommunicate with the transaxle 42. For example, the control system 44may receive signals from the transaxle 42 to indicate whether atransition between shift positions is occurring. The control system 44may also communicate with a battery control module of the tractionbattery system 50, or other control devices.

Additionally, the electric drive system 25 may include one or morecontrollers 54, such as an inverter system controller (ISC). Thecontroller 54 is configured to control specific components within thetransaxle 42, such as the generator 16 and/or the motor 36, such as forsupporting bidirectional power flow. In one embodiment, the controller54 is an inverter system controller combined with a variable voltageconverter (ISC/VVC).

FIGS. 2 and 3 illustrate an exemplary battery module 60 that can beincorporated into an electrified vehicle. For example, the batterymodule 60 may be employed within the battery system 50 of theelectrified vehicle 12 of FIG. 1. The battery system 50 could includeany number of battery modules 60 for supplying electrical power to theelectric machines 16, 36 of the electrified vehicle 12 (see FIG. 1). Thenumber of battery modules 60 employed by the battery system 50 is notintended to limit this disclosure and could vary depending on the typeof electrified vehicle 12.

One or more battery cells 62 may be stacked relative to one another toconstruct the battery module 60. The battery cells 62 may be stackedupright, on their sides, or in any other configuration. The batterycells 62 are prismatic, lithium-ion cells, in one non-limitingembodiment. Other battery cell types may also be utilized within thescope of this disclosure. Each battery cell 62 includes two terminals 65that project outwardly from the battery cell 62. Cell interconnects 63(see FIG. 3) may be utilized to electrically connect adjacent batterycells 62 in parallel. The cell interconnects 63 may extend in a singleplane above the battery cells 62. In one embodiment, the parallel pairsof battery cell 62 may be connected in series with other battery cell 62pairs.

Heat may be generated by each battery cell 62 during charging anddischarging operations. Heat may also be transferred into the batterycells 62 during key-off conditions of the electrified vehicle 12 as aresult of relatively extreme (i.e., hot) ambient conditions. The batterymodule 60 may therefore include a battery thermal management system 99for thermally managing the battery cell 62 over a full range of ambientconditions.

In one embodiment, the battery thermal management system 99 includes oneor more heat spreaders 64 (see FIG. 3) and coolant channels 66, a supplymanifold 68 and a return manifold 70. As discussed in greater detailbelow, waste heat may be transferred from the battery cells 62 to theedges of the heat spreaders 64 and subsequently dissipated via a heattransfer medium M communicated through the coolant channels 66.

The heat spreaders 64 provide heat transfer across a wrap axis 72 (seeFIG. 2) of the battery cells 62. In one embodiment, one heat spreader 64is sandwiched between two adjacent battery cells 62. The heat spreaders64 can be fixedly attached to the battery cells 62 in any known manner.In one embodiment, the battery module 60 includes a plurality of batterycells 62 and a plurality of heat spreaders 64, with at least one heatspreader 64 interspersed between adjacent battery cells 62.

The heat spreaders 64 could embody any size or shape. The total number,size and shape of the battery cells 62 and the heat spreaders 64 are notintended to limit this disclosure.

In one embodiment, the heat spreaders 64 are aluminum or copper sheets.In another non-limiting embodiment, the heat spreaders 64 are aluminumencapsulated annealed pyrolytic graphite plates. In another embodiment,the heat spreaders 64 are flexible graphite sheets. In yet anotherembodiment, the heat spreaders 64 are aluminum or steel. For example, analuminum or steel battery casing may serve as a heat spreader. The heatspreaders 64 have a relatively high thermal conductivity in order toconduct heat out of the battery cells 62. Other thermally conductivematerials (e.g., heat pipes) may also be suitable for the heat spreaders64.

One coolant channel 66 may be attached to each side of the heat spreader64. The coolant channels 66 may be connected to the heat spreader 64 inany known manner, including but not limited to, soldering, brazing, orby using thermal grease. If the battery cells 62 incorporateelectrically active metal cases, the heat spreaders 64 may beelectrically isolated from the battery cells 62 using, for example, thinplastic coatings. The coolant channels 66 may also extend across anentire length L of the battery module 60 (see top view of FIG. 3). Inother words, the coolant channels 66 define a single conduit along eachside of the battery module 60.

A heat transfer medium M may be communicated through the coolantchannels 66 in order to remove heat that has been conducted out of thebattery cells 62 through the heat spreaders 64. The heat transfer mediumM may be a liquid coolant. In one non-limiting embodiment, the heattransfer medium M includes 60% ethylene glycol and 40% water. However,other heat transfer mediums or coolants may be suitable for thisapplication.

The heat transfer medium M is transferred to the supply manifold 68. Thesupply manifold 68 communicates the heat transfer medium M to thecoolant channel 66 prior to exiting through the return manifold 70. Inone embodiment, the supply manifold 68 is near a bottom 74 of thecoolant channel 66 and the return manifold 70 is near a top 76 that isopposite from the bottom 74. In the illustrated embodiment, the heattransfer medium M travels vertically from the bottom 74 toward the top76 of the coolant channel 66 (see FIG. 2). However, an oppositeconfiguration is also contemplated in which the heat transfer medium Mflows downwardly within the cooling channel 66 from the top 76 towardthe bottom 74 (see FIG. 4). In another embodiment, the return manifold70 extends in a plane that is above the plane of the cell interconnects63.

The battery cells 62 as well as the various other components of thebattery module 60 are supported by a base 78. The base 78 is a supportstructure that transfer loads experienced by the battery module 60 intoa battery support frame (not shown).

A vacuum insulation panel (VIP) 80 may be mounted to the base 78. TheVIP 80 insulates the base 78 and protects the battery cells 62 fromambient temperatures. The VIP 80 may include a relatively low thermalconductivity for thermally isolating the battery cells 62 fromvariations in ambient conditions.

A film heater 82 may be positioned to extend between the battery cells62 and the VIP 80. In other words, the film heater 82 may be located atthe bottom of the battery cells 62. The film heater 82 is selectivelyactuated ON to heat the battery cells 62, such as during extremely coldambient conditions. In one embodiment, the film heater 82 is apositive-temperature-coefficient (PTC) film heater, although otherheating devices are also contemplated.

FIG. 5 illustrates a coolant channel 166 of a battery thermal managementsystem 99. In this disclosure, like reference numbers designate likeelements where appropriate and reference numerals with the addition of100 or multiples thereof designate modified elements that are understoodto incorporate the same features and benefits of the correspondingoriginal elements

A heat spreader 64 extends between a first battery cell 62A and a secondbattery cell 62B. The coolant channel 166 is connected to an edge 94 ofthe heat spreader 64.

In one embodiment, the coolant channel 166 includes at least oneaugmentation feature 90. The augmentation features 90 increase the heattransfer effect between the heat transfer medium M (see FIG. 2) and thecooling channel 166. The augmentation features 90 are formed on orextend from an inner wall 92 of the coolant channel 166. Theaugmentation features 90 could include a plurality of fins 96 thatdiagonally extend across the coolant channel 166. However, otheraugmentation features having different configurations could beincorporated into the design, including but not limited to fins,turbulators, dimples or other features.

FIG. 6 schematically illustrates operation of the battery thermalmanagement system 99 as part of a closed loop system in order tothermally manage the battery cells 62 of multiple battery modules 60 ofa battery system 50. The battery thermal management system 99 mayinclude a central supply line 102 and a central return line 104. Thecentral supply line 102 and the central return line 104 may extend atany location relative to the battery modules 60 of the battery system50. In one non-limiting embodiment, the central supply line 102 and thecentral return line 104 extend along a center of the battery system 50between horizontally adjacent battery modules 60.

The central coolant supply line 102 delivers the heat transfer medium Mto the supply manifolds 68 (see FIGS. 2-3), which supply the coolantchannels 66. The central coolant return line 104 is in fluidcommunication with the return manifolds 70 (see FIGS. 2-3) for expellingthe heat transfer medium M from the battery system 50 after removingheat from the battery cells 62 of each battery module 60.

The heat transfer medium M may be stored within a tank 106. A pump 108circulates the heat transfer medium M through the closed loop batterythermal management system 99.

A heat exchanger 84 may be positioned downstream from the central returnline 104. The heat transfer medium M can therefore be communicated tothe heater exchanger 84 after it has been communicated through thecoolant channels 66 to remove heat from the battery cells 62. Afterbeing cooled by the heat exchanger 84 (for example, using a separaterefrigeration unit, not shown), the heat transfer medium M may bereturned to the central supply line 102 to recirculate the heat transfermedium M for removing additional heat from the battery cells 62.

In one non-limiting use, the battery thermal management system 99 canheat the battery cells 62 in response to a first temperature conditionTC1 (i.e., relatively cold ambient temperatures) and cool the batterycells 62 in response to a second temperature condition TC2 (i.e.,relatively hot ambient temperatures). The first and second temperatureconditions TC1 and TC2 can be sensed by the control system 44 (see alsoFIG. 1), which may be in communication with the thermal managementsystem 99. The control system 44 may actuate the film heater 82 (shownschematically in FIG. 6) ON in response to sensing the first temperaturecondition TC1. The film heater 82 heats the battery cells 62 whenactuated ON. The battery cells 62 may need heated during non-operationof the electrified vehicle, such as during the winter months of colderclimates. The heat transfer medium M may not be circulated through thebattery thermal management system 99 in response to the firsttemperature condition TC1.

The film heater 82 is commanded OFF in response to sensing the secondtemperature condition TC2. The heat exchanger 84 may be used to cool theheat transfer medium M in response to sensing the second temperaturecondition TC2. The cooled heat transfer medium M may then be returned tothe central supply line 102 for cooling the battery cells 62. Heat fromthe battery cells 62 is dissipated into the heat transfer medium M as itis communicated inside the coolant channels 66. The battery cells 62 mayneed cooled during relatively hot ambient temperatures, such as duringsummer months or in warmer climates.

Although the different non-limiting embodiments are illustrated ashaving specific components or steps, the embodiments of this disclosureare not limited to those particular combinations. It is possible to usesome of the components or features from any of the non-limitingembodiments in combination with features or components from any of theother non-limiting embodiments.

It should be understood that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould be understood that although a particular component arrangement isdisclosed and illustrated in these exemplary embodiments, otherarrangements could also benefit from the teachings of this disclosure.

The foregoing description shall be interpreted as illustrative and notin any limiting sense. A worker of ordinary skill in the art wouldunderstand that certain modifications could come within the scope ofthis disclosure. For these reasons, the following claims should bestudied to determine the true scope and content of this disclosure.

What is claimed is:
 1. A battery thermal management system, comprising:a heat spreader; a coolant channel attached to said heat spreader; asupply manifold fluidly connected with said coolant channel andconfigured to supply a heat transfer medium to said coolant channel; anda return manifold fluidly connected with said coolant channel andconfigured to expel said heat transfer medium from said coolant channel.2. The system as recited in claim 1, wherein said heat spreader is incontact with a battery cell.
 3. The system as recited in claim 1,comprising a plurality of battery cells and a plurality of heatspreaders, at least one of said plurality of heat spreaders interspersedbetween adjacent battery cells of said plurality of battery cells. 4.The system as recited in claim 1, wherein said heat spreader is anannealed pyrolytic graphite plate or a flexible graphite sheet.
 5. Thesystem as recited in claim 1, comprising a second coolant channelattached to an opposite edge of said heat spreader from said coolantchannel.
 6. The system as recited in claim 1, comprising a vacuuminsulation panel beneath said heat spreader.
 7. The system as recited inclaim 6, comprising a film heater on a first side of said vacuuminsulation panel and a base on a second side of said vacuum insulationpanel.
 8. The system as recited in claim 1, wherein said heat transfermedium is a liquid coolant.
 9. The system as recited in claim 1, whereinsaid coolant channel includes at least one augmentation feature.
 10. Thesystem as recited in claim 1, comprising a central supply line thatdelivers said heat transfer medium to said supply manifold and a centralreturn line that communicates said heat transfer medium away from saidcoolant channel.
 11. A battery system, comprising: a battery modulehaving at least one battery cell; and a battery thermal managementsystem configured to heat said at least one battery cell with a filmheater in response to a first temperature condition and cool said atleast one battery cell by transferring heat into a heat spreader inresponse to a second temperature condition.
 12. The system as recited inclaim 11, wherein said battery thermal management system includes: saidheat spreader adjacent to said at least one battery cell; a coolantchannel attached to said heat spreader; a supply manifold near a firstside of said coolant channel, and a return manifold near a second sideof said coolant channel.
 13. The system as recited in claim 12, whereinsaid battery thermal management system include a heat exchangerconfigured to cool a heat transfer medium communicated through saidcoolant channel.
 14. The system as recited in claim 11, wherein saidbattery thermal management system includes a base that supports said atleast one battery cell.
 15. The system as recited in claim 14,comprising a vacuum insulation panel mounted to said base.
 16. Thesystem as recited in claim 15, wherein said film heater is positionedbetween said vacuum insulation panel and said at least one battery cell.17. A method, comprising: transferring heat from a battery cell to aheat spreader; conducting the heat from the heat spreader into a coolantchannel; and dissipating the heat into a heat transfer mediumcommunicated inside the coolant channel to thermally manage the batterycell.
 18. The method as recited in claim 17, comprising the step ofsensing a temperature condition of the battery cell.
 19. The method asrecited in claim 18, comprising the step of heating the battery cell inresponse to the temperature condition indicating a cold ambientcondition.
 20. The method as recited in claim 18, comprising commandingthe dissipating step in response to the temperature condition indicatinga hot ambient condition.